It is already known, in an internal combustion engine having an actuating member in the air supply for adjusting an air mass to be supplied to the engine, to adapt a position of the actuating member by means of a short-time adaptation to an instantaneous operating state and to adapt a position of the actuating member by means of a long-time adaptation for compensating longer-term influence quantities on the position of the actuating member. Here, a long-time adaptation value for the position of the actuating member is formed in the long-time adaptation in dependence upon a minimum short adaptation value for the position of the actuating member with this short adaptation value being formed in the short-time adaptation.